This goal of the UCSD Infectious Disease training program is to prepare physician-scientists trained in Internal Medicine or Pediatrics for independent academic careers in infectious diseases and related disciplines. In its first 25 years, this training program focused primarily on laboratory-based biomedical research. Since 1995 the training program has evolved to include, in addition, patient oriented medical research as scientific opportunities in this area have increased and as an increasing number of faculty have been recruited with expertise in translational and clinical research. Over the past 5 years 5 trainees have participated in a rich and structured training environment ranging from bench to applied biomedical research. Since 2004 there have been several notable developments. Firstly, leadership of the Adult Division of Infectious Diseases and of this Training Grant has been passed from Dr. Joshua Fierer to Dr. Robert Schooley who assumed these roles in 2005 and 2006, respectively. Dr. Victor Nizet now leads the pediatric infectious disease training efforts supported by this grant. Secondly, over the past 5 years, an influx of faculty with research efforts both in the U.S. and in international settings has provided significant new training opportunities in basic and patient oriented medical research related to international medicine. With these new and expanding training opportunities in international medicine, the training program has been reorganized into three tracks focusing on microbial pathogenesis (led by Drs. Joshua Fierer and Donald Guiney), patient oriented medical research (led by Drs. Constance Benson and Richard Haubrich) and international medicine (led by Drs. Joseph Vinetz and Steffanie Strathdee). Finally, the size of the training program in Adult Infectious Diseases has increased from 2 to 3 new postdoctoral fellows per year seeking 1 year of clinical training and 2-4 years of research training. In this application we are requesting renewal of of support for six postdoctoral trainees per year for the coming five years.